large and growing body of experimental evidence suggesting that vitamin E supplementation may reduce the risk of some chronic diseases, especially heart disease, the results of the GISSI Prevenzione Trial (GISSI-Prevenzione Investigators, 1999), the Heart Outcomes Prevention Evaluation (HOPE) study (HOPE Study Investigators, 2000), and the Alpha-Tocopherol Beta-Carotene (ATBC) Cancer Prevention Study (ATBC Cancer Prevention Study Group, 1994) preclude recommendations for higher vitamin E intakes at this time.
High levels of physical activity and sports might increase oxidative damage and thus increase needs for antioxidants. It is unknown whether or the extent to which increased oxidative damage occurs in physical exercise. However, the Boston Nutritional Status Survey reported that plasma vitamin E concentrations increased slightly with regular exercise in adults 60 years of age and older (Hartz et al., 1992). It is, therefore, not known if any adjustment in vitamin E requirements is needed in response to strenuous or regular exercise.
Given the minimal data available to develop the EAR, adjusting any recommendations for vitamin E requirements to meet expected needs for individuals with extreme variation for reference body size or composition must await additional data.
Potentially injurious free radicals are present in cigarette tar and smoke (Church and Pryor, 1985; Pryor and Stone, 1993). In addition, cigarette smokers have increased phagocyte activities (Eiserich et al., 1997). Smokers are therefore under a high and sustained free-radical load, both from cigarette smoke itself and from oxidants produced by activated phagocytes (Cross et al., 1997; Duthie et al., 1991; Eiserich et al., 1995).
Exposure to cigarette smoke damages antioxidant defenses. Low blood levels of vitamin C are a characteristic feature of heavy smokers (Duthie et al., 1995, 1996; Mezzetti et al., 1995; Ross et al., 1995). Cigarette smoke also damages low molecular weight thiols and especially thiol-containing proteins in human plasma (O'Neill et al.,